Wnt1 Promotes Cementum and Alveolar Bone Growth in a Time-Dependent Manner

The WNT/β-catenin signaling pathway plays a central role in the biology of the periodontium, yet the function of specific extracellular WNT ligands remains poorly understood. By using a Wnt1-inducible transgenic mouse model targeting Col1a1-expressing alveolar osteoblasts, odontoblasts, and cementoblasts, we demonstrate that the WNT ligand WNT1 is a strong promoter of cementum and alveolar bone formation in vivo. We induced Wnt1 expression for 1, 3, or 9 wk in Wnt1Tg mice and analyzed them at the age of 6 wk and 12 wk. Micro–computed tomography (CT) analyses of the mandibles revealed a 1.8-fold increased bone volume after 1 and 3 wk of Wnt1 expression and a 3-fold increased bone volume after 9 wk of Wnt1 expression compared to controls. In addition, the alveolar ridges were higher in Wnt1Tg mice as compared to controls. Nondecalcified histology demonstrated increased acellular cementum thickness and cellular cementum volume after 3 and 9 wk of Wnt1 expression. However, 9 wk of Wnt1 expression was also associated with periodontal breakdown and ectopic mineralization of the pulp. The composition of this ectopic matrix was comparable to those of cellular cementum as demonstrated by quantitative backscattered electron imaging and immunohistochemistry for noncollagenous proteins. Our analyses of 52-wk-old mice after 9 wk of Wnt1 expression revealed that Wnt1 expression affects mandibular bone and growing incisors but not molar teeth, indicating that Wnt1 influences only growing tissues. To further investigate the effect of Wnt1 on cementoblasts, we stably transfected the cementoblast cell line (OCCM-30) with a vector expressing Wnt1-HA and performed proliferation as well as differentiation experiments. These experiments demonstrated that Wnt1 promotes proliferation but not differentiation of cementoblasts. Taken together, our findings identify, for the first time, Wnt1 as a critical regulator of alveolar bone and cementum formation, as well as provide important insights for harnessing the WNT signal pathway in regenerative dentistry.

Temporomandibular joint involvement in patients with juvenile idiopathic arthritis: a retrospective chart review

OBJECTIVE

To study the proportion of patients with temporomandibular joint (TMJ) involvement among patients with juvenile idiopathic arthritis (JIA), as well as associated clinical characteristics and signs/symptoms.

METHOD

We performed a retrospective chart review on consecutive patients followed in the Hamburg Centre for Paediatric and Adolescent Rheumatology Eilbek between January 2010 and July 2012. TMJ involvement was diagnosed based on clinical examination; a subgroup of patients was also assessed by magnetic resonance imaging (MRI).

RESULTS

The study included 2413 patients with JIA (52.1% girls, mean age at JIA onset 9.5 years). The most frequent JIA category was oligoarthritis (46.6%), followed by enthesitis-related arthritis (ERA; 38.1%). TMJ involvement was diagnosed in 843/2413 patients (34.9%) (677 MRI-confirmed, four not MRI-confirmed, no MRI examination in 162). Female gender (p = 0.017), higher number of additional joints with active arthritis (p < 0.001), anti-nuclear antibody (ANA) positivity (p = 0.005), higher age (p = 0.020), and oligoarthritis (persistent and extended; p = 0.043) were significantly associated with TMJ involvement. Human leucocyte antigen-B27-positive patients were less likely to have TMJ involvement (p = 0.023). Pain on palpation and pain while chewing were statistically significantly associated with TMJ involvement (p = 0.008 and p = 0.020, respectively).

CONCLUSIONS

Based on our findings, to identify TMJ involvement special attention should be paid to JIA patients with female gender, ANA positivity, and oligoarthritis, as well as those with a higher number of additional joints with active arthritis; and regular examinations of the TMJ should be performed.

Rsk2, the Kinase Mutated in Coffin-Lowry Syndrome, Controls Cementum Formation

The ribosomal S6 kinase RSK2 is essential for osteoblast function, and inactivating mutations of RSK2 cause osteopenia in humans with Coffin-Lowry syndrome (CLS). Alveolar bone loss and premature tooth exfoliation are also consistently reported symptoms in CLS patients; however, the pathophysiologic mechanisms are unclear. Therefore, aiming to identify the functional relevance of Rsk2 for tooth development, we analyzed Rsk2-deficient mice. Here, we show that Rsk2 is a critical regulator of cementoblast function. Immunohistochemistry, histology, micro-computed tomography imaging, quantitative backscattered electron imaging, and in vitro assays revealed that Rsk2 is activated in cementoblasts and is necessary for proper acellular cementum formation. Cementum hypoplasia that is observed in Rsk2-deficient mice causes detachment and disorganization of the periodontal ligament and was associated with significant alveolar bone loss with age. Moreover, Rsk2-deficient mice display hypomineralization of cellular cementum with accumulation of nonmineralized cementoid. In agreement, treatment of the cementoblast cell line OCCM-30 with a Rsk inhibitor reduces formation of mineralization nodules and decreases the expression of cementum markers. Western blot analyses based on antibodies against Rsk1, Rsk2, and an activated form of the 2 kinases confirmed that Rsk2 is expressed and activated in differentiating OCCM-30 cells. To discriminate between periodontal bone loss and systemic bone loss, we additionally crossed Rsk2-deficient mice with transgenic mice overexpressing the osteoanabolic transcription factor Fra1. Fra1 overexpression clearly increases systemic bone volume in Rsk2-deficient mice but does not protect from alveolar bone loss. Our results indicate that cell autonomous cementum defects are causing early tooth loss in CLS patients. Moreover, we identify Rsk2 as a nonredundant regulator of cementum homeostasis, alveolar bone maintenance, and periodontal health, with all these features being independent of Rsk2 function in systemic bone formation.

Homepages of German dental schools - a target group-oriented evaluation

INTRODUCTION

The Internet represents the central communication medium in higher education. University applicants, students, teachers and scientists use the Internet when seeking information on medicine. The homepages of dental schools are not just sources of information, but also a means of presenting the school. No comparative studies have been undertaken concerning the content and extent of their Internet sites so far.

METHODS

Based on the literature and assessments of medical school websites, 136 criteria were defined within the setting of a Delphi procedure and drawn upon for a standardised evaluation of the websites of all 30 German dental schools. Structure and extent of the content of the websites were evaluated. Possible influencing factors, such as financial resources and number of applicants, were investigated.

RESULTS

The results yielded by the homepages varied considerably. The best Internet site received 84% of the possible points, the poorest 38%. On average, 62% of the criteria were fulfilled. Influencing factors, such as the amount of funding by the particular state government, could not be detected. Two-thirds of the dental schools addressed students, three-fourth teachers and scientists as target groups. More than 50% did not address applicants. Specific requirements regarding barrier-free accessibility of information were hardly met.

CONCLUSIONS

Individual faculties already have homepages of a high quality; for others, there is a need for improvement. General recommendations for university websites should be discussed at the European level to ensure a uniform standard of quality. The criteria presented here offer faculties the possibility to reflect upon their own Internet sites.

Is high-resolution ultrasonography suitable for the detection of temporomandibular joint involvement in children with juvenile idiopathic arthritis?

OBJECTIVES

The purpose of this study was to determine the potential of high-resolution ultrasonography for the detection of temporomandibular joint (TMJ) changes in children with juvenile idiopathic arthritis (JIA).

METHODS

We investigated prospectively 20 children (17 female and 3 male; mean age 11.06 years, standard deviation 3.43 years) with TMJ disorders caused by JIA, over a period of 16 months. Using a 12 MHz array transducer, four images in each TMJ (160 images) were acquired. Each image was analysed with regard to five different aspects (condylar erosion, thickness of the condylar disc, synovial thickness, joint effusion and enlargement of the intra-articular space).

RESULTS

Diagnosis of JIA was ensured for every child and involvement of the TMJ was proven by MRI. Overall 287 changes (35.9%) were detected by using high-resolution ultrasonography. On 124 images (77.5%) condylar erosions were diagnosed; on 55 images (34.4%) synovial thickness was abnormal; on 48 images (30%) we could see higher thickness of the condylar disc; on 40 images (25%) irregularities of the bony surface were detected; and on 20 images (12.5%) we found joint effusion.

CONCLUSION

High-resolution ultrasonography could be a sufficient diagnostic method, especially for the detection of condylar involvement in children with JIA, even if not all parts of the TMJ are visible for ultrasonography. High-resolution ultrasonography is a valuable tool in particular situations: (i) when MRI examination is not available; (ii) when children fear MRI examination; (iii) in more advanced stages of JIA; and (iv) for monitoring the progression of TMJ involvement and response of therapy.

Associations between orthopaedic disturbances and unilateral crossbite in children with asymmetry of the upper cervical spine

The objective of the present study was to detect possible associations between unilateral crossbite and orthopaedic disturbances in children with asymmetry of the upper cervical spine. Fifty-five children aged 3-10 years (22 girls and 33 boys) with a unilateral crossbite and 55 gender- and age-matched children with a symmetric occlusion but no crossbite, who served as the control group, were selected from an orthopaedic cohort of 240 patients. In all children, asymmetry of the upper cervical region was confirmed by radiographs and palpation. The following orthopaedic aspects were investigated: oblique shoulder and pelvis, scoliosis, functional leg length difference, and laxity of ligaments of the foot. The differences between the groups were analysed by means of an unpaired t-test. An increased occurrence of orthopaedic parameters in the frontal plane was observed in children with a unilateral malocclusion. A unilateral crossbite was not necessarily combined with a pathological orthopaedic variable, but statistically, children with a unilateral malocclusion showed more often an oblique shoulder (P = 0.004), scoliosis (P = 0.04), an oblique pelvis (P = 0.007), and a functional leg length difference (P = 0.002) than children with symmetry. The results suggest that a unilateral crossbite in children with asymmetry of the upper cervical spine is associated with orthopaedic disturbances. There is no evidence of a causal link.

The release of nickel from orthodontic NiTi wires is increased by dynamic mechanical loading but not constrained by surface nitridation

The influence of dynamic mechanical loading and of surface nitridation on the nickel release from superelastic nickel-titanium orthodontic wires was investigated under ultrapure conditions. Commercially available superelastic NiTi arch wires (size 0.018 x 0.025'') without surface modification (Neo Sentalloy) and with nitrogen ion implantation surface treatment (Neo Sentalloy Ionguard) were analyzed. Mechanical loading of wire segments with a force similar to the physiological situation was performed with a frequency of 5 Hz in ultrapure water and saline solution, respectively. The release of nickel was monitored by atomic absorption spectroscopy for up to 36 days. The mechanically loaded wires released significantly more nickel ( approximately 45 ng cm(-2) d(-1)) than did nonloaded wires (<1 ng cm(-2) d(-1)). There was no statistically significant effect of the testing solution (water or NaCl) or of the surface nitridation. The total amount of released nickel was small in all cases, but may nevertheless account for the occasional clinical observations of adverse reactions during application of NiTi-based orthodontic appliances. The surface nitridation did not constrain the release of nickel from NiTi under continuous mechanical stress.

Long-term evaluation of orofacial function in children with Down syndrome after treatment with a stimulating plate according to Castillo Morales

The aim of this investigation was to evaluate the long-term orofacial development of Down children who received plate therapy according to Castillo Morales in their early childhood. The orofacial development of 27 Down children was documented before and after plate therapy and at a follow-up examination 13 years +/- 6 months after initiation of therapy. The orofacial appearance significantly improved during therapy (p = 0.00). During the follow-up, mouth posture remained stable (p = 0.259), whereas tongue position further improved (p = 0.034). A better long-term development was documented in children with initial severe orofacial dysfunctions.

Orthodontic springs and auxiliary appliances: assessment of magnetic field interactions associated with 1.5 T and 3 T magnetic resonance systems

The objective of this paper is to evaluate magnetic field interactions at 1.5 and 3 T for 20 orthodontic devices used for fixed orthodontic therapy. Twenty springs and auxiliary parts made from varying ferromagnetic alloys were tested for magnetic field interactions in the static magnetic field at 1.5 and 3 T. Magnetic translational force F(z) (in millinewtons) was evaluated by determining the deflection angle beta [American Society for Testing and Materials (ASTM standard test method)]. Magnetic-field-induced rotational force F(rot) was qualitatively determined using a five-point scale. beta was found to be >45 degrees in 13(15) devices at 1.5(3) T and translational force F(z) exceeded gravitational force F(g) on the particular object [F(z) 10.17-261.4 mN (10.72-566.4 mN) at 1.5(3) T]. F(z) was found to be up to 24.1(47.5)-fold higher than F(g) at 1.5(3) T. Corresponding to this, F(rot) on the objects was shown to be high at both field strengths (> or = +3). Three objects (at 1.5 T) and one object (at 3 T) showed deflection angles <45 degrees , but F(rot) was found to be > or = +3 at both field strengths. For the remaining objects, beta was below 45 degrees and torque measurements ranged from 0 to +2. Of 20 objects investigated for magnetic field interactions at 1.5(3) T, 13(15) were unsafe in magnetic resonance (MR), based on the ASTM criteria of F(z). The implications of these results for orthodontic patients undergoing MRI are discussed.

Evaluation of an antimicrobial and fluoride-releasing self-etching primer on the shear bond strength of orthodontic brackets

The enhanced risk of dental caries is one negative side-effect of fixed appliances. A new antimicrobial and fluoride-releasing self-etching bonding system (Clearfil Protect Bond) has been introduced in restorative dentistry and clinical studies have already shown the potential for this primer to be used clinically with effective antiplaque properties. Therefore, this in vitro study was conducted in order to evaluate the new primer in comparison with a conventional bonding preparation. One hundred and twenty extracted human teeth were randomly divided into three groups of 40 specimens each (20 incisors, 20 premolars). In group 1 a conventional bonding procedure was used (etching, Transbond XT), in group 2 the new primer was used according to the manufacturer's recommendations when bonding to intact enamel, while in group 3 the new primer was used without prior etching. Shear bond strength (SBS) was measured with a universal testing machine and the adhesive remaining after debonding was determined using an optical microscope at x10 magnification. The adhesive remnant index was used in order to assess the mode of failure. No enamel fractures were detected in any of the specimens. In all groups acceptable bond strengths were observed. The only statistically significant difference (P = 0.004) was found for the incisors in group 2, which showed the highest mean SBS (17.46 MPa). Considering the acceptable bond strength and the mode of failure, use of the new primer without prior etching is recommended in patients with fixed appliances. Further in vivo studies will be carried out in order to evaluate clinical performance.

[Orthodontic brackets in high field MR imaging: experimental evaluation of magnetic field interactions at 3.0 Tesla]

PURPOSE

To evaluate static magnetic field interactions for 32 commonly used orthodontic brackets in a 3.0 T magnetic resonance imaging (MRI) system.

MATERIALS AND METHODS

32 orthodontic brackets consisting of a steel alloy (n = 27), a cobalt-chromium alloy (n = 2), ceramic (n = 1), ceramic with a steel slot (n = 1), and titanium (n = 1) from 13 different manufacturers were tested for magnetic field interactions in a static magnetic field at 3.0 T (Gyroscan Intera 3.0 T, Philips Medical Systems, Best, Netherlands). The magnetic deflection force F (z) [mN] was evaluated by determining the deflection angle beta [ degrees ] using the established deflection angle test according to the ASTM guidelines. The magnetic-field-induced rotational force F (rot) or torque was qualitatively determined using a 5-point grading scale (0: no torque; + 4: very strong torque).

RESULTS

In 18 of the 32 brackets, the deflection angle beta was found to be > 45 degrees and the translational force exceeded the gravitational force F (G) on the particular bracket (F (z): 1.2 - 45.7 mN). The translational force F (z) was found to be up to 68.5 times greater than the gravitational force F (G) (F (z)/F (G): 1.4 - 68.5). The rotational force F (rot) was correspondingly high (+ 3/+ 4) for those brackets. For the remaining 14 objects, the deflection angles were < 45 degrees and the torque measurements ranged from 0 to + 2. The static magnetic field did not affect the titanium bracket and the ceramic bracket. No measurable translational and rotational forces were found.

CONCLUSION

Of the 32 brackets investigated for magnetic field interactions at 3.0 T, 18 (56.25 %) were unsafe in the MR environment according to the ASTM guidelines. However, the forces measured were minimal compared to the forces generally necessary for dislodging these bonded orthodontic brackets from tooth surfaces. The implications of these results for orthodontic patients undergoing MR examinations at 3 Tesla are discussed.

Cephalometric Evaluation of Children with Down Syndrome After Early Intervention with the Stimulating Plate

The aim of stimulating plate therapy in patients with trisomy 21 is to correct orofacial dysfunctions and prevent the establishment of subsequent morphological characteristics such as protrusion of the incisors and pseudoprognathia. This study investigated the effectiveness of this type of therapy in improving skeletal traits of patients with Down syndrome. The lateral cephalograms of 22 consecutive juveniles with Down syndrome, whose orofacial dysfunctions had been successfully treated with a stimulating plate according to Castillo Morales in infancy (17 months +/- 24 months), were examined 136 months on average (minimum of 78 months, maximum of 231 months) after initiation of treatment. In 16 of the 22 patients, the anomaly-typical bialveolar protrusion of the anterior teeth was diagnosed. The cephalometric results indicated larger values of cephalometric parameters concerning cranial base and maxilla, and markedly larger mandibular cephalometric values when compared to untreated children with Down syndrome. These results show that a stimulating plate may not always be indicated in patients with Down syndrome with a skeletal Class III pattern and minor orofacial findings.

Dentomaxillofacial imaging in Proteus syndrome

Proteus syndrome is a rare condition that involves atypical growth of the bones, skin and head and a variety of other symptoms. Only a few authors have reported on the craniofacial manifestations so far. The authors present a case of a 7-year-old girl with Proteus syndrome in which the facial skeleton showed unilateral overgrowth. The analysis of the radiological evaluation revealed a bialveolar prognathism, a skeletal class III, a dolicocephalic growth pattern and a left convex face scoliosis. On the left side, the lesser wing of the sphenoid was elevated and the ethmoidal cell complex was hypertrophic. The left ramus and body of the mandible were enlarged. The asymmetric dental development with a precocious dental age on the affected side was the most striking feature on the panoramic view. Early diagnosis and therapy depend on clinical evaluation and imaging. Therefore, further evaluations on the craniofacial features of patients with Proteus syndrome are necessary in order to establish a list of characteristic symptoms.

An optimized synthetic substrate for orthodontic bond strength testing

OBJECTIVE

The purpose of this study was to investigate the suitability of different synthetic calcium phosphate based substrates as a biomimetic enamel surface model for orthodontic bond strength testing.

METHODS

Carbonated apatite, amorphous calcium phosphate and commercial hydroxyapatite specimens were prepared as substrates for orthodontic bond strength testing. Carbonated apatite specimens were prepared by pressing, sintering and treatment with NaF. The shear bond strength was measured with a universal testing machine.

RESULTS

Hydroxyapatite, amorphous and cold pressed carbonated hydroxyapatite exhibited fractures within the substrate after debonding. Mean bond strength values for carbonated hydroxyapatite were 7.38 (1.75) MPa for specimens pressed at 300 degrees C and 9.55 (2.23) MPa for specimens pressed at 300 degrees C and then sintered at 600 degrees C. An additional NaF treatment after sintering resulted in lower bond strength measurements of on average 6.52 (1.03) MPa.

SIGNIFICANCE

Hot pressed and sintered carbonated hydroxyapatite showed acceptable shear bond strength values and may represent a suitable biomimetic model for orthodontic bond strength testing.

Influence of orthodontic appliances on myofunctional therapy

Various removable and fixed orthodontic appliances were rated by interview and questionnaire by 42 myofunctional therapists in the Hamburg area with respect to their influence during myofunctional therapy. The Nance holding arch was given the most negative rating of all appliances covering the palate area. For the active plate, marking the rest position of the tongue by roughening the acrylic surface or by reproducing the palatal relief was considered beneficial. The quadhelix expansion device and Hyrax palatal expander were rated as unfavorable because of their positioning in the palatal area. Among the functional appliances, Fränkel's function regulator was given the best rating. Regular fixed appliances (brackets, bands) were not considered a disturbance. Habit reminders (plates and spurs) were given a very negative rating by ca. 80% of the therapists because they disturbed the myofunctional exercises and led to adaptive dysfunctions. Since many patients with dysfunction of the orofacial musculature undergo simultaneous myofunctional and orthodontic therapy, treatment planning and choice of orthodontic appliances should be carefully coordinated.

Optimizing interdisciplinary cooperation for patients with orofacial dysfunctions. Presentation of an interdisciplinary diagnostic referral sheet

BACKGROUND

The quality of interdisciplinary cooperation is one of the most important factors in the success and long-term stability of treatment of patients suffering from orofacial dysfunctions. However, speech pathologists have criticized the poor communication and diagnostics at the time of referral and have requested a standardized diagnostic referral sheet with the aim of improving interdisciplinary cooperation.

DIAGNOSTIC REFERRAL SHEET

The diagnostic referral sheet presented here is based on the demands of speech pathologists focusing on myofunctional therapy and helps in initial assessment of the individual situation and necessary treatment. It is subject to continuous updating and coordinates the many medical disciplines involved on account of the complex pathology.

CONCLUSION

The multidisciplinary diagnostic referral sheet, which is independent of treatment methods and compressed into one page, is aimed at contributing to quality assurance and to the improved documentation of orofacial dysfunctions.

Postretention changes in canine position. Results of a long-term follow-up

The aim of the present study was to evaluate sagittal, vertical and transverse changes in canine position and a possible correlation with relapse of lower anterior crowding. From a sample with a long-term follow-up of 15.7 +/- 4.4 years after treatment, patients with a full dentition were enrolled in the study. Post-treatment and long-term follow-up casts of 117 patients were measured and statistically analyzed. A decrease in intercanine width was found between post-treatment and long-term follow-up records, with more lingual inclination of the mandibular canine axis in the transverse plane. There was a significant correlation between maxillary and mandibular canine inclination. Concomitant changes were an increase in lower anterior crowding and a decrease in mandibular intercanine width. Relapse of anterior crowding has a multifactorial etiology. The results of this study suggest a possible influence of the canines. Functional causes in particular might have a profound influence and should be considered during treatment planning.

Early orthodontic treatment of Class-III malocclusion in Germany

In order to evaluate current attitudes to early interceptive treatment, 2001 orthodontic offices in Germany were asked to fill in a questionnaire comprising the following topics: indication, appliances for the early correction of Class-III malocclusions, diagnostic records, duration, and benefits to overall therapy. Based on the 677 evaluable questionnaires, the following statistically significant conclusions could be drawn: 92.6% of the orthodontists see Class-III malocclusion as an indication for early treatment. Early treatment of severe crowding, diastemata, Class-II malocclusion, deep bite, increased overjet and impacted incisors was declined by most orthodontists. The interceptive treatment of further malocclusions was controversially discussed. Functional appliances (67.5%), in particular the Fränkel III (47.3%), were dominant in correction of Class-III malocclusions. Typical orthodontic records relating to early interceptive treatment include panoramic radiographs, lateral headfilms, photos and dental casts. 2.5% of the orthodontists routinely take a hand-wrist radiograph. Although recently published studies support the use of facial masks in theory, they are rarely used in practice. To what extent early interceptive treatment of Class-III malocclusion influences the overall treatment is the subject of further studies.

Condylar restoration after early TMJ fractures and functional appliance therapy. Part II: Muscle evaluation

The aim of this study was to analyze and to describe the condition of the lateral pterygoid muscle during and after functional appliance therapy in children who had sustained condylar fractures. The treatment group consisted of 19 patients with an average age of 13.4 years, who had sustained a unilateral fracture at an average age of 8.4 years and had been treated functionally for 6 to 8 months. Muscle condition was assessed through axial soft tissue description. The volume and density of the lateral pterygoid muscle were measured in both groups and were compared on the basis of sex, age and fracture type. 74% of the patients in the follow-up group showed muscle differences of more than 10% between the 2 sides. In 2/3 of these patients the lateral pterygoid of the fracture side was 13 to 69% smaller. The volumes of the contralateral pterygoid muscles in the 2 patient groups differed by 10% on the basis of sex. Both in the treatment group and in the follow-up group the volume difference between the healthy and fractured side was as high as 70% depending on localization and type of fracture. Deep fractures and fractures with complete dislocation of the condyle evoked the most serious reduction in muscle volume.

Effect of early orthopedic intervention on hemifacial microsomia patients: an approach to a cooperative evaluation of treatment results

The purpose of the present study was to analyze the effects of early orthopedic intervention in patients with hemifacial microsomia, clinically as well as radiologically, by computed tomographic examination to assess soft and hard tissue temporomandibular joint changes. Five patients, one with mandibular dysostosis, one with otomandibular dysostosis, two with Goldenhar syndrome, and one with a surgically revised fibroma of the right mandible that was reconstructed by a costochondral graft, were treated by means of an activator functional appliance. During functional appliance treatment, all patients showed improvement of function and occlusion, and facial asymmetry was reduced. Spiral computed tomographic examination before and during treatment provided data on the bony and muscular deficiencies. The volume and density of the lateral pterygoid muscle was measured with the standard computed tomography software. Evaluation of soft and hard tissue conditions before treatment has shown that the most important factor "lack of soft tissues" can be compensated by excellent cooperation during functional therapy. Pretreatment volume of the affected lateral pterygoid muscle in all patients was significantly smaller than on the unaffected side. In three patients, volume measurements between 4 and 8 years demonstrated that the lateral pterygoid muscle on the affected side had a third, less than a third, and a fifth of the volume of the unaffected side. Although increase, stability, and decrease of the ratio of left and right condylar dimension, muscular volume, and density were found, long-term prognosis cannot be given in the cases with extreme muscular deficiencies after cessation of growth. Prepubertal orthopedic treatment success is a desirable and feasible presurgical or nonsurgical treatment goal for the interdisciplinary team approach. From a study of the pathologic, we learn much about the normal.

Condylar restoration after early TMJ fractures and functional appliance therapy. Part I: Remodelling

The aim of this study was to measure quantitatively and to analyze the process of condylar restoration during and after functional appliance therapy with an activator in children and juveniles who had sustained condylar fractures. Spiral computed measurement of condylar morphology was performed in order to quantify the association described in the literature between condylar remodelling and age as well as certain types of fracture. Nineteen patients with an average age of 13.4 years, who had sustained a functionally treated unilateral condylar fracture 4.9 years earlier on average, were included in the present study as the follow-up group. Twenty patients, who had sustained a unilateral fracture at an average age of 8.1 years and had been treated functionally for 6 to 8 months, formed the treatment group. The condylar dimension and the condylar neck length of the ipsilateral and of the contralateral temporomandibular joints were measured from the axial and parasagittal reconstructions and were compared on the basis of sex, age and fracture type. The mediolateral condylar dimension of the follow-up group showed a sex-specific difference of 0.2 cm on the contralateral side and 0.4 cm on the ipsilateral side. The fracture side condyle indicated a relative mediolateral decrease of 4.2% and an anteroposterior increase of 12.6%. Shortening of the condylar neck and excessive bony overgrowth were found to occur more often in fractures with displacement and in low fracture types. The "10-plus" subgroup at time of trauma showed a significantly greater variation and greater differences in mediolateral and anteroposterior condylar dimension than the younger patients.

The role of extraction in stability of orthodontic treatment

Long-term postretention assessment of orthodontically treated cases has been of interest for 5 decades; however, extraction versus nonextraction follow-up studies are difficult to compare without regard to sample structure, therapy concept und different parameters. The results of selected studies- extraction of 1 or 2 incisors, of premolars and of second and third molars, early and late extraction therapy and serial extraction-showed that long-term postretention stability is not a realistic treatment goal. The Cologne long-term records allow optimistic prediction: relative stability has been found in the majority of former patients, irrespective of the kind of treatment and treatment time. Original anomaly, type (extraction/nonextraction) and amount of treatment, and end-of-treatment alignment were found to be major factors influencing dentoalveolar and skeletal post-treatment changes. The conclusion is that therapy-induced post-treatment changes can be reduced by having a treatment goal within the anatomic limits.

Retention and stability considerations for adult patients

This article gives an overview of generally accepted and special concepts of the last and often life-long treatment-phase in adult orthodontics, the retention phase. The secret of successful adult orthodontics lies in adult-specific principles of histology and physiology and the interrelation of joint, occlusion, and muscles, which helps define the requirements of proper diagnosis, mechanics, and retention. Retention in adults should include maintenance of tooth position, overall dental health, and a periodontal status that can be attained by combinations of several retention concepts: retention appliances and surgical and restorative retention procedures. Short- and long-term postretention follow-up studies have shown that there is no guarantee for long-life stability after orthodontic tooth movements in adults without an anomaly- and treatment--specific retention phase.

Treatment and postretention changes in dental arch width dimensions--a long-term evaluation of influencing cofactors

The aim of the present long-term follow-up study of orthodontically treated patients was to analyze postretention changes in arch width dimension and to isolate factors that may serve as predictors of long-term prognosis. Pretreatment, end-of-treatment, and postretention (at least 10 years) models of 226 cases with different malocclusions were used to measure intercanine and intermolar width, arch length, sum of the mesiodistal dimension of the incisors, irregularity index, crowding, molar and canine relationship, overjet, and overbite. To assess the influence of initial and end-of-treatment alignment, kind of treatment (extraction versus nonextraction) and the amount of expansion in postretention stability, the sample was divided into different subgroups. The findings indicate that postretention arch width relapse occurred more frequently in the upper intermolar (25.8%) and lower intercanine region (23.9%) than in the lower intermolar (19.0%) and upper intercanine (13.8%) region. Pretreatment and posttreatment alignment as well as the kind of treatment and the amount of expansion were found to be influencing factors. The study concludes by proposing a reassessment of the definition of stability. The influence of the pretreatment anomaly, kind of treatment, amount of expansion, and posttreatment alignment on long-term stability should be recognized. Patients should be apprised of treatment limitations before treatments.

Post-retention crowding and incisor irregularity: a long-term follow-up evaluation of stability and relapse

The aim of the present long-term follow-up study of orthodontically-treated patients (mean: 15.7 years) was to analyse post-retention changes and to reveal factors which may play a role as predictors for long-term prognosis. Pretreatment, end-of-treatment, and post-retention models of 226 cases with all types of anomaly were used to measure intercanine and intermolar width, arch length, and sum of the mesiodistal dimension of the incisors, Irregularity Index, crowding, molar and canine relationship, overjet, and overbite. In order to assess the influence of sex, initial and end-of-treatment alignment, type of therapy, amount of tooth movement, and presence of third molars on the extent of post-retention changes, the total sample was divided into subgroups. Findings indicated that post-retention crowding and incisor irregularity increased more frequently in the mandible than in the maxilla. Pretreatment variables such as increased mesiodistal incisor dimension, severe crowding and incisor irregularity, arch length deficiency, arch constriction, and increased overbite as well as post-treatment spacing, arch expansion, increased arch length, and residual Class II or III molar relationships were found to be associated factors in the process of post-retention increase of crowding and incisor irregularity. 'Overexpansion' was found to be a factor in mandibular incisor relapse.

[A retrospective evaluation of the treatment of skeletal Class-II with removable appliances]

Pre- and post-treatment lateral radiographs of 120 former patients with skeletal class II, who had been treated with either an Andresen/Häupl type activator or bite jumping plates, were selected for this study. The evaluation results showed that bite jumping plates had a significant inhibition on the forward downward growth and the anterior rotation of the maxilla. The increase of the SNB-angle was significantly higher and there was also more posterior rotation of the maxilla in those patients, who had been treated with an activator. A two-way analysis of variance was carried out and it was possible to show that the independent treatment factors explained only 1/5 to 1/3 of the overall variance of the sample. The differences among the patients seem to depend more on individual growth patterns than just on the type of removable appliance.

[A critical evaluation of the functional treatment of mandibular neck fractures in children. The results of a spiral computed tomographic follow-up]

In this retrospective follow-up study after 6 months of treatment with functional appliance therapy of 12 children who had suffered condylar fractures, spiral CT was employed for the radiological examination with 2D and 3D reconstructions. Although all patients exhibited restoration of normal function, only 4 showed favorable remodeling. The other patients had developed 5 hypoplastic, 5 moderate and 5 severe deformed condyles. Seven condylar fragments were resorbed; 2 were uprighted; 4 had developed bony spurs and 3 neoarthrosis. The results revealed a fracture dependent remodeling. The authors discuss the etiology of the functional stimulated new bone formation of the condylar process. Excessive bone apposition as a reaction to the anterior shift of the mandible seems to play an important role during the overgrowth of the head of the condyle.

CT analysis of temporomandibular joint state in children 5 years after functional treatment of condylar fractures

This retrospective study assessed the temporomandibular joint (TMJ) state of children who had suffered unilateral condylar fractures at least 5 years before and had been treated by functional orthopedic methods alone. The sample group were examined radiologically by computed tomography (CT) spiral scans which were reformatted to two-dimensional (2-D) images in different anatomic planes and to 3-D reconstructions in various projections. Although the seven patients who formed the sample group showed good-to-excellent functional results, the quantitative and qualitative analysis of the scans revealed alterations of size, shape, bony remodeling, and position of the condyle on the fracture side, as well as adaptive changes of the temporal component of the joint. We recommend spiral CT for assessment of TMJ disorders and fractures of the condyle at the time of injury and for follow-up assessment.

[A retrospective examination of the acceptance of removable appliances]

In order to study the subjective attitudes of patients and their parents to orthodontic treatment questionnaires were handed out to both groups. One hundred and forty five patient questionnaires and those answered by 114 parents formed the base of the study. The majority of the patients were only able to provide partial answers to precise questions about their treatment. Speech impairment, pressure, and salivation were given as being the most vexatious aspects of the treatment. The majority of the patients and the majority of parents favored removable appliances over fixed appliances. The patients' social environment did not negatively influence their attitude to orthodontic treatment.